The invention starts from a switching network as is described in an article by M. A. Henrion et al, "Switching Network Architecture for ATM Based Broadband Communications", XIII International Switching Symposium, June 1990, Vol. V, pages 1-8.
That article describes a three-stage switching network in which multiple paths are possible for a connection from an input link to an output link. Each stage of the switching network consists of several switching modules, and each switching module is equivalent to a 128.times.128 switching matrix or a 32.times.32 switching matrix. The first stage is formed by a number of switching modules connected in parallel, which are called "access switches". These switching modules are designed to evenly distribute the traffic to the subsequent stages of the switching network. The switching function proper is performed by the other two stages, which also consist of a number of parallel-connected switching modules each. The switching modules of the three stages are interconnected via hard-wired paths. Each of the switching modules includes a circuit for fault detection. If this circuit detects a fault in the switching module, it will send a particular signal backward to all preceding switching modules. This signal calls upon the receiving switching module to stop sending data cells to the faulty switching module. In this manner, the faulty switching module is isolated, so that the operational capability of the switching network is preserved.
The disadvantage of this self-isolation mechanism is that in the event of a failure of a switching module, a major number of other switching modules may no longer be available for the execution of switching functions, either. Therefore, the failure of a major number of switching modules must be taken into account in dimensioning the switching network, i.e., the switching network must be correspondingly overdimensioned.